Online payment transactions have greatly facilitated the purchase of goods, services, and the movement of money over the Internet. In online payment transactions, multiple parties are frequently involved. For example, a user may use a portable device to access a merchant's website to make purchases and to request that payments for the purchases be transferred from the user's account with a payment provider such as PayPal to the merchant's account. To complete the purchase, the user needs to authorize the payment transaction with the payment provider. Authorization of the payment transaction may require the user to enter identification information such as a PIN (Personal Identification Number) that is known only to the user and the payment provider so that the payment provider may authenticate the user. However, there are times when the payment provider may receive the identification information from a third party. For example, a user may desire to make multiple purchases from a merchant at different times. To facilitate online payment transactions for multiple purchases from the same merchant or for scenarios where the user may be unavailable to authorize each payment transaction, it is desirable to allow a user to pre-approve future payment or payments to an online merchant prior to the purchase. Payment pre-approval enables the user to return multiple times to a merchant to make purchases without having to return to the payment provider to authorize a payment for each purchase. To prevent fraudulent purchases by unauthorized users using the pre-approved payment, the payment provider may require identification information of the user from the merchant or other third party for the payment provider to authenticate the transaction. The identification information may be information that is disclosed by the user only to the merchant or other third party such that revealing the identification information to the payment provider may breach the confidentiality of the information. Therefore, it is desirable to enable authentication in transactions involving multiple parties while allowing the parties to maintain the confidentiality of information shared between the parties.